1. Field of the Invention
The present invention relates to sealing gasket arrangements and more particularly to sealing between the porthole in a manhole riser and a horizontally extending pipe connected to the porthole.
2. Description of the Prior Art
Prior art patents bearing some similarity to the present invention include U.S. Pat. Nos. 3,406,988; 3,656,771; 3,700,265; 3,759,280; 3,866,925; and 3,958,280. These patents variously relate to the provision of annular elastomeric gaskets which sealingly fit between the end of a pipe and the hole in another member for preventing leakage between the hole and the exterior of the pipe. In particular, U.S. Pat. Nos. 3,406,988; 3,759,280 and 3,958,313 disclose the use of sleeve-like gaskets having the exteriors at one end sealed to the wall of the hole and the opposite end sealed to either the interior or exterior of a joined pipe. The sealing of the one end to the wall of the hole is also variously achieved, one technique being to cast a radial flange on the sleeve into the concrete of the body containing the hole, and another being to clamp this flange against the exterior of the wall containing the hole by means of a steel or the like clamping ring. Still another arrangement involves inserting the gasket loosely into a hole followed by inserting an expandible split ring inside the gasket and then radially forcing the ring to an enlarged, expanded size for radially compressing the gasket against the wall of the hole. A still further arrangement is to drive a tapered tubular wedge into the gasket loosely installed in the hole for radially compressing the gasket against the wall of the hole.